Tratamento térmico de normalização em tampos de vasos de pressão fabricados de material P275NH

In a market environment increasingly competitive, the companies need to control of this process accurately, avoiding rework or rejection of materials during industrialization. This can be achieved by defining procedure that assure the maintenance of the materials characteristics, as specified initially in the projects. This graduation work has the objective of defining the best heat treatment parameter of normalizing for Heads, part of a pressure vessel, formed in P275NH material. The methodology applied is based on the execution of a sequence of Heat Treatments, using different parameters. The process variables were the cooling velocity, the hold time and the hold temperature variation. As a result of this study, it is noticed that the mechanical properties of the materials are strongly influenced by the hold temperature variation and by the cooling velocity, both determined for the heat treatment cycle

Análise do perfil de dureza e microestrutura de um aço forjado AISI A2 submetido a tratamento térmico com resfriamento em água

Due to the large use of steel in several processes around the world, there is the increasingly concern to find new materials and/or optimization and improvement of the processes, as the need to reduce the cost and a productivity increase in the primary industry, such as the siderurgy. The rolling is the most used mechanical process in the world and therefore is required the development of new tools in high volume and with optimum characteristics to support the market demand. Forged rolls used are for rolling. These rolls have heat treatment that has the purpose to achieve the appropriated mechanical properties to support the variables of the rolling process. The objective of this work is to analyze the hardness profile and the microstructure a tool steel similar to AISI A2, forged in an opened die process and submitted to heat treatment with water-cooling. The results allowed plotting a hardness profile and performing a microstructure analysis, and whereby to confirm that the heat treatment is not a quenching, but it is a material beneficiation by the hardening of superficial layer, since there is no martensitic microstructure. Therefore, this paper provides the support to future studies about the possibility to perform enhancements in this thermal heat made in the rolls produced at Gerdau Plant in Pindamonhangaba

Usinagem do alumínio da classe 6005 com uso de ferramenta cerâmica

The machining process is so much important in the economic world. Many machining parameters have been studied to maximize results, in terms of cost and lifetime. (decrease of cutting tool wear, improved surface finish, among others). The objective of this study is to evaluate the wear of a ceramic tool in the machining of the aluminum alloy 6005 A. The analysis of the wear of the cutting tools is very important due to its big impact on the final finishing of the piece as a whole. The evaluation took place in two stages, first it was done a detailed study of the literature of the whole machining process, where the study of the formation and swarf classification were among the most important steps in this phase. The second step consisted in the machining of the piece of aluminum 6005 A with a ceramic cutting tool constituded of aluminum oxide and magnesium oxide with silicon carbide impregnation. The swarf generated in this process was then photographed with a Zeiss optical microscope and analyzed for its size and shape. Through this comparison it was concluded that the swarf are generated shear swarfs, shaped like a tangled, fragmented and arcs connected, thus classifying the material as medium difficulty machining. Through the image analysis tool it was concluded that the parameter of lower wear was the: Vc = 500m / min, f = 0.10mm / rev and ap = 0.5mm

Análise microestrutural e caracterização mecânica do aço AISI 4350 submetido a diferentes tratamentos térmicos

The multiphase steels are gaining increasing attention in scientific studies because of the different mechanical and microstructural properties that the material can achieve under different thermomechanical and heat treatments that can be submitted. In the present study, it was made a microstructural study thru the triple attack technic associated with optical microscopy and mechanical characterization of medium carbon AISI 4350 steel thru a tensile strength test, subjected to three routes of heat treatment: annealing, quenching and tempering and isothermal annealing. It was verified the predominance of ferrite-perlite constituent in the specimen annealed, martensitic in the quenched and tempered specimen and bainitic in the annealed isothermally specimen. The annealed material showed a higher ductility, while the hardened and tempered specimen showed the highest hardness and ultimately the bainitic specimen showed a combination of the two abovementioned mechanical properties. Thus, we proved that the multiphase steel SAE 4350 can be a versatile material with great potential for various industrial applications

Torneamento da liga de alumínio da classe 6005 utilizando ferramenta cerâmica

Machining processes are one of the most important manufacturing processes in the modern world. In these processes, there are many elements which will influence in the final result of the machined part. Among them, the tools are the principal factor of the rising cost, because its global influence on the process. In aeronautical industries, this can be more evidenced due the need to machining several alloys, between them, aluminum alloys. These alloys have to demonstrate a specific surface finishing to be used in aircraft's fuselage. This kind of industry is one of the segments which is still rising in Brazil, and they are looking viable alternatives in the manufacturing processes of materials, due the need to produce more and more parts and equipment, with costs increasingly reduced. The purpose of this project is the development of a ceramic with differentiated properties. The ceramics were developed using a pre-sintering at 1200 °C, with posterior sintering at 1600°C, and subjected to dry turning process on aluminum alloy 6005. The characterizations showed that ceramics presented with toughness on the center of 1700 MPa and on the surface of 1950 MPa, density 98,5 ±0,14. g/cm³. Ceramics were grinded and faceted, according to ISO standard 1832, and subjected to turning tests in a ROMI lathe brand, model GL240M, using cutting speeds of 500, 800 and 1000 m/min with different feed rates. The machining results showed low occurrence of flank wear to all cutting speeds, and better surface finishing average values of Ra = 0,4935 μm and Rt = 8,112 μm. In general, it could be seen that the tool presents important potential to machining 6005 alloy, and that the use of correct parameters can decrease and/or eliminate subsequent processes, providing important reductions in costs related to the machining processes

Análise e comparação de orelhamento na liga AA3104 após laminação a quente

Aluminum has been widely used in the forming and manufacture of beverage cans, specific aluminum alloy AA3104, which manufacturers are increasingly demanding as to mechanical properties, quality and reducing waste. This work describes the analysis and comparison of the behavior of earing AA3104 aluminum alloy samples of final thicknesses of 1.80 and 2.10 mm. Were obtained after a hot rolling process, a total population of 86 samples for the two different thicknesses, of which 23 samples of 1.80 mm and 2.10 mm 63 samples. After removal of samples, there was a mechanical test inlay, then characterizing the earing in them. The results earing to the thicknesses of 1.80 and 2.10 mm were analyzed and compared statistically to give 7.1% and 7.4% on average, respectively, correlated with the hot rolling process variables, showing that they are statistically equal and that the process variables do not affect the end result desired, ranging from 7.0 to 7,5%

Caracterização da liga Ti-30Ta após tratamento biomimético associado à incorporação de antibiótico

Surface treatments have been used to modify the surface of titanium alloys. The purpose of this study is to evaluate the surface of Ti-30Ta alloy after biomimetic approach associated to antibiotic incorporation. The ingots were obtained in arc melting furnace, treated and cold-worked by swaging. The surface treatment was performed in two steps: biomimetic treatment and antibiotic incorporation. For biomimetic treatment, first an alkaline treatment (NaOH 1M at 60ºC) was performed, followed by heat treatment and immersion in SBFx5 (Simulated Body Fluid) for a period of 24 hours. In order to incorporate the antibiotic, samples were immersed in a solution formed by drugs plus SBFx5 for 48 hours. The sample surfaces were analyzed by scanning electron microscopy (SEM), X-Ray diffraction (XRD), atomic force microscopy (AFM) and contact angle measurements. The release of antibiotic from coated implants was measured in phosphate buffer saline at pH 7.4 by using UV/VIS spectrometry. Results have shown changes on the surface after incorporating the drug, which is gradually co-precipitated with the Ca-P crystals, forming a uniform and rough layer on the metal surface

Influência do peróxido e do uso de diferentes substâncias de combate à dor na inflamação e na expressão de neuropeptídeos pró-inflamatórios após o tratamento clareador

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)